Tubular brzdge



EDEN A. BALDWIN, 0F ELMIRA, NEW YORK.

TBULAR BRIDGE.

Specification of `]'.ettersPatent No. 1`1,467-da`ted .August 8, 1854.

To all 'whom t may concern:

Be it known that I, EDEN A. BALDWIN, of Elmira, in the county of Chemung and State of New York, have invented anew and Improved Mode of Constructing Tubular Bridges for Railroads and otherPurposes; and I do hereby declare that the following is a full, clear, and exact description thereof, reference bein had to the accompanying drawings, making part of this specication, in which- Figure l is a longitudinal elevation, Fig. 2 a transverse section, and Fig. 3 a longitudinal section.

' The principle of my invention consists in constructing a tube of suficient diameter for the passage of a railway train, `using'planks or other suitable timbers, placed longitudinally and doweled together, and the whole irmly bound with strong iron rods or hoops. For this purpose I propose to use oak plank two or three inches thick as the size or strength of the bridge may require and of uniform width. The hoops or bands to be made of l or 1?,- inch iron rods, which are 'rst made of the necessary form and size arch, and as an additional security against their becoming displaced by any strain. Each plank is doweled to the next one with `strong wooden pms a', a', one foot apart.

When a portion of the tube is complete, the bands are tightened, so as to render itsecure, by an arrangement shown at Fig. 5.' A is a swivel upon one end of the band.` B is the opposite end passing through the swivel, and the screw-nut, C, which is round or Octagon, and projects artly through the lowermost plank of the ridge in a mortise made for that purpose, through which a lever can be inserted 1n holes in the nut and by turning it thus, from the inside, draw up the bands to the utmost degree of tension required.

It may be found advantageous to use al framework in the interior, or ribs `like those seen in the model, to *facilitate the building, but if used they should be removed when the structure is complete. As they form no addition to the strength of the bridge ando Fig. 1 shows the general external appeary ance of a bridge of this construction twenty feet in diameter spanning a distance of two hundred feet. A railroad track runs through the interior, and a walk for footmen over the top. It is built slightly arching, to compensate for any deflection which might take place from the shrinkage of the timber or its contraction under the weight to which it is subjected.

Fig. 2 is a transverse and Fig. 3 a longitudinal section. The same letters refer to like parts. a a is the walk, b b the planks or timbers forming the tube, c c the railroad track, d Z the framework for its support within the bridge. This is so braced that the weight of a passing train bears only on the part directly withinv the bands, so that the strain does not come upon any given point of the `woodwork but is equalized generally, and the direct weight upon the bands f serves to bind the whole more `lirmly together. The railway track may be laid over the top, without diminishing its strength, in situations where it is more expedient to build it` below the level of the road. l

The advantages of my plan consist in the simplicity and economy of construction, the thorough equalization of the strain on all parts;` it resists lateral vibration as well as vertical, thus `adapting it peculiarly to situations `exposed to strong wind and dispensingwith piers,as its capacity for spanning longdistances is limited only by the power of the material to resist the crushing force of its own weight and that which it is intended to sustain.

What I claim as my invention and desire to secure by Letters Patent is* Constructing a pridge `by the combination of the longitudinal strips of wood, the transverse iron bands and the arrangement for tightenin the lsaine from the inside by a scribed, and forming a cylindrical or tubuscrewv an swivel, withY the trestle or framelar bridge ofgreat strength, durability and Work for supporting a railroad track and simplicity of construction.

receiving the strain directly on the bands,y EDEN A. BALDWIN. 5 Whether. the track be 'placed Within the Witnesses:

bridge or upon its top; the Whole arranged HIRAM POTTER,

and combined substantially as herein del I. FRASER. 

